Electric baseboard heating unit



March 21, 1961 N. J. BURGER ET AL 2,976,389

ELECTRIC BASEBOARD HEATING UNIT 3 Sheets-Sheet 1 Filed Jan. 19, 1959 lllllllll II l I I I I I l l I k l n I I l l I I II INVENTORS +3 N/cHoLas J 50126412.

BY JOHN J. FINN FIB.Z

A1- rakus Y March 21, 19 1 N. J. BURGER ET AL 2,976,389

ELECTRIC BASEBOARD HEATING UNIT Filed Jan. 19, 1959 3 Sheets-Sheet 2 INVENTOILS Mcuoma J fiukasz BY J'oH/v JZ F/N/s March 21, 1961 N. J. BURGER ETAL 2,976,389

ELECTRIC BASEBOARD HEATING UNIT 5 Sheets-Sheet 3 Filed Jan. 19, 1959 a u v val INVENTORS V cuazns J. BURGER- BY J HN J FIN/V VIM ATTORNEY United States Patent ELECTRIC BASEBOARD HEATING UNIT Nicholas J. Burger, Silver Spring, and John J. Finn, R0ckville',;Md., assignors to Electra-Therm, Inc, Silver Spring', Md.

Filed Jan. 19, 1959, Ser. N0. 787,617 7 Claims. (Cl. 219-44) This invention relates to electric radiators, and more particularly to an electrical baseboard heating unit.

A main object of the invention is -to provide a novel and improved electrical: baseboard heating unit which is simple in construction, which is eflicient in operation, and which has high heat transmission capacity without being required to operate at a high temperature.

A further object of the invention is to provide an improved electrical' baseboard heating unit which is inexpensive to manufacture, which is easy to assemble, which is rugged inconstruction, and. which involves only a few parts;

A- still further object of the invention is to. provide an improved electrical baseboard heating unit which is relatively compact in size, which is inconspicuous in appearance, which operates at a safe temperature, and which is economical in power consumption.

, Further objects'and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

Figure 1 is a perspective view of an improved electrical baseboard heating unit constructed in accordance with the present invention.

Figure 2 is a vertical cross-sectional view taken longitudinally through the baseboard heating unit on the line 22 of- Figure 1.

Figure 3 is an enlarged transverse vertical cross-sectional view taken on line 33 of Figure 2.

Figure 4 is an enlarged transverse cross-sectional view taken on line 4-4 of Figure 2..

Figure 5 is an enlarged fragmentary elevational view taken on line 5+5 of Figure 4.

Figure 6 is a fragmentary front elevational view, partly in vertical cross-section, of a modified form of heat-transmitting core assembly employed in a baseboard unit according to the present invention.

I Figure 7' is an enlarged transverse vertical cross-sectional view taken on the line 7-7 of Figure 6.

Figure 8 is a fragmentary front elevational view, partly in vertical cross-section, of another modification of a heat-transmitting core assembly according to the present invention.

Figure 9 is a fragmentary vertical longitudinal crosssectional view taken through another modification of a heat-transmitting core assembly according to this invention.

Figure 10 is an enlarged cross-sectional detail view taken on line 10*10 of Figure 9 showing the cold positions of the parts.

Figure 11 is a fragmentary cross-sectional view similar to Figure 10, showing the hot positions of the parts.

Figure 12 is a fragmentary enlarged transverse vertical cross-sectional view similar to Figure 3, but showing another modification of the present invention.

Figure 13 is a fragmentary cross-sectional view taken on line 13-43 of Figure 12.

Referring to the drawings, and more particularly to Figures 1 to 5, 11 generally designates an improved elec- 2 tric heater according to this invention. The heater 11 comprises a generally rectangular, horizontally elongated housing 12 having a vertical rear wall 13, a horizontal bottom wall 14, a horizontal top wall 15, vertical end walls; 16 and 17, and a removable front wall element 18 which: is secured by sheet metal screws 25, 25 at its opposite ends to respective inturned vertical flanges 19 and 20 formed on the intermediate portions of the front edges of end walls 16 and 17. The front wall element 18 is of substantially lesser height than rear wall 13 and is supported on the flanges 19 and 20 to define a horizontally elongated lower inlet opening 21 and a horizontally elongated upper air outlet opening 22.

Designated generally at 23 is a horizontally elongated electrical heating unit which is mounted in the space between front wall element 18 and rear wall 13, being spaced inwardly from the wall members 18 and 13. Designated at 24 is an upwardly and forwardly inclined, arcuate, horizontally elongated baflie plate which is concave forwardly and which is mounted in the upper portion of housing 12 above and parallel to heating unit 23 and which faces the air outlet opening 22.

Baflie member 24 may be supported in any suitable manner, for example, may be secured to horizontal tubul'ar supporting sleeves 26 rigidly secured to rear wall 13. Thus, member 24 is formed with bosses 27 through which extendfastening screws 28 threaded into the sleeves 26,

the ends of the sleeves 26 being bevelled, as shown in Figures. 3 and 4, and the bosses 27 being shaped to align axially with said sleeves, whereby the screws 28 clamp the bafile member in the inclined position illustrated.

The. heating unit 23 comprises an intermediate, horiz'onta'lly elongated heat radiating member 29 consisting of a pair of reflective metal plate members 30, 30 suitably secured together in face-to-face relation, as by welding or thelikc, and formed with pairs of opposing channels 31, between which are snugly received the upper and lower arms 32, 32 of a generally U-shaped heating element 33 of conventional construction, and which may comprise a helical resistance conductor embedded in a compacted mass of refractory insulating material, said conductor having the respective end terminals 34, 34.

Additional horizontally elongated reflective metal plate members 35 and 36 aredisposed on the opposite sides of the radiating member 29 in spaced parallel relation thereto. A plurality of spaced transverse horizontal tubular rivets 38 of substantial diameter extend through the members 29, 35 and 36 midway between the arms 32, 32, spacer sleeves 37 being mounted on the rivets between the horizontally elongated members 35, 29 and 29, 36. Thus, the tubular rivets 38 cooperate with the spacer sleeves 37 to rigidly secure the members 35, 29 and 36 in spaced parallel relation, as is clearly shown in Figures 3' and 4.

Transverse horizontally extending rod members 39 are rigidly secured to rear wall 13 and extend through the horizontal tubular rivets 38, supporting the heating unit 23 ina vertical position between front wall element 18 and rear wall 13. The rod members 39 are formed at their ends with short upwardly inclined detent portions 40 which are engageable with the forward ends of the tubular rivets 38 to limit forward movement of the heating unit. The detent portions 40 are short enough to allow the rivets to receive the rod members 39 when the device is assembled, as will be presently described.

Respective hook-like tongue elements 41 are struck inwardly from the upper portion of the rear wall 13 and supportingly engage through horizontal slots 42 formed in the upper end portions of the plate member 36, the slots being of suflicient height to allow the tongues 41 to be engaged therethrough while the rod members 39 are being received in the tubular rivets 38. Abutment tongues 43 are struck inwardly from the lower portion of rear wall 13 and are located to engage the lower marginal portion of plate member 36, cooperating with the detent portions 40 to limit the heating unit 23' to a position spaced inwardly from rear wall 13 and front wall element 18 such as is illustrated in Figures 3 and 4. Thus, abutment tongues 43 cooperate with rod members 39 and tongue elements 41 to support the horizontally elongated heating unit 23 in a vertical position, as shown.

The members 35, 29 and 36 may be preassembled and secured together by means of the tubular rivets 38 and spacers 37 as above described, after which the arms 32 of heating element '33 may be slipped through the tubular passages defined by the opposing channels 31. Suitable lugs 45 may then be secured on the terminals 34, 34. The heating unit 23 may then be mounted in the housing 12 by engaging rods 39 through the tubular rivets 38 and engaging the tongues 41 in the slots 42. The terminals 34 and lugs 45 may be engaged through openings 46 in a side wall of an outlet box 47, secured in one end of the housing 12, and said lugs may be connected to respective terminals 48, 48 provided on an insulated terminal block 49 provided in the outlet box, whereby energizing conductors from the domestic electric power lines may be connected to the heating element 33.

After the installation of the heating unit 23 in the housing 12 and the electrical connections thereof to the energizing conductors have been completed, the front wall element 18 is secured to the flanges 20, 20 by means of the sheet metal screws 25, 25, whereby the device is ready for operation.

In operation, when the heating element 33 is 61181? gized, heat is transmitted therefrom by direct conduction to the intermediate radiator member 29 which is thus raised to substantially the same temperature as the heating element, the heat being distributed substantially to all parts of the member 29 at the same rate so that all parts of the member 29 are at substantially this temperature. Thus, there are no local high temperature areas on the member 29.

Member 29 radiates heat to the adjacent plate members 35 and 36, which are substantially the same size as member 29 and are located sufficiently close to member 29 to be also elevated to almost the same temperature as member 29. Plate members 35 and 36 have reflective surfaces which face the opposing reflective surfaces of the member 29, so that heat is re-radiated back and forth between the member 29 and the adjacent plate. members35 and 36, but there is sufficient conduction by the tubular rivets 38 and absorption by the members 35 and 36 to heat up the relatively thin plate members 35 and 36.

Air enters the bottom inlet opening 21 and flows upwardly by convection through the spaces adjacent the vertical heating members 35, 29 and 36, being heated thereby and being deflected outwardly through the discharge opening 22 by the inclined arcuate baffle member 24. Since the heating members 35, 29 and 36 are of substantial area and the vertical spaces defined adjacent thereto are relatively long, heat is transferred to the air efiiciently, uniformly, and with a minimum amount of turbulence, even though the heating members 35, 29 and 36 are at a relatively moderate temperature.-

Since the surfaces of the members 35, 29 and 36 are at substantially uniform temperatures, theflow of air.

is relatively even and the air emerges from the upper discharge opening 22 at substantially the same temperature along the length of said opening.

Although the members 35, 29 and 36 have relatively large heat transfer areas, the vertical, parallel arrangement of these members provides minimum resistance to air flow, allowing rapid circulation of air through the heater and minimizing the tendency for dust to be deposited on the heat transfer surfaces thereof.

Figure 6 illustrates a modified form of heating unit wherein the intermediate member, shown at 29', comprises a pair of plates 30', 36' secured together in faceto-face relation and formed with opposing U-shaped channels 31', 31' between which is permanently housed the heating element 33. The front and rear plate members 35 and 36 are secured in spaced parallel relation to the intermediate member 29' by transverse tubular rivets 38 and spacer sleeves (not shown) in the same manner as:

of the heating elements are provided with terminal lugs 45, whereby the series-connected heating elements may be energized from the domestic power lines in the same manner as in the embodiments of Figures 1 to 7.

While the outer plate members 35 and 36 are elevated considerably in temperature, they are not quite at the same temperature as the inner plate member containing the electrical heating element. Therefore, where the baseboard heater is of considerable length, the problem of different longitudinal expansions of the inner plate member and the outer plate members must be consid-;

ered, because in the case of a long unit there may be suflicient differences in total longitudinal expansion to set up undesirable stresses in the heating unit and to cause warping, buckling, or other undesirable distortion of the core assembly.

Figure 9 illustrates a form of the invention wherein the core assembly, designated generally at 60, is of substantial length and comprises an inner two-ply metal plate member 61 formed with opposing channels 62 to define bores receiving the upper and lower arms 63, 63 of an elongated conventional electrical heating element 64. Disposed at opposite sides of the inner plate member 61 in parallel spaced relation thereto are the respective elongated plate members 65 and 66 (Figure 10).-

' plate member, said tubes being of progressively increasing diameters toward the opposite ends of the plate member. 71 and are rigidly secured at their outer ends to the Q outer plate members 65 and 66, the rivets being substantially in contact with the inside surf-aces of the spacer tubes but being substantially smaller in diameter than said tubes. When the unit is cold, the rivets substantially engage the outer side portions of the spacer tubes (relative to the center line 67 as shown in Figures 9 and 10,

but when the unit is hot, said rivets engage the inner side portions of the spacer tubes, as shown, for example, in Figure 11, since the longitudinal expansion of the inner plate member 61 is greater than that of the outer plate members and 66. The progressively increasing diameters of the spacer tubes outwardly from the center line 67 provides progressively greater clearance for longitudinal thermal expansion of the inner plate member, since the expansion is cumulative. In the hot condition of the unit, the rivets 72 substantially engage the inner side portions of the sleeves 68 to '71 (relative to the center line 67), whereby rattling or vibration of the core assembly components is minimized. The same is true in the cold condition of the unit, since the rivets 72 substantially engage the outer side portions of the sleeves Sleeves 68 to 71 terminate closely adjacent to thej Tubular rivets 72 extend through the tubes 68 toare thus able to transmit heat thereto at their edges as well as through the associated rivets 72. I

.In the ease of a relatively long baseboard heating assembly', longitudinal expansion of the core assembly in its housing may be substantial, and therefore it is desirable to provide longitudinally yieldable means to support the core assembly in the housing. Thus, as shown in Figures l2 and 13, the core assembly 60 may be supported in its housing 12' by generally L-shaped swingable supporting rods 73 having rearwardly projecting top pivot lugs 74 engaged through pivot openings 75 provided in the top marginal portion of the baffle plate 24. The horizontal bottom arms 76 of the supporting rods are engaged through the tubular rivets 72 and are provided at their ends with short upstanding detent lugs 77 engageable against the rear flanges 78 of the rivets, but allowing free pivoting of the arms 76 in the rivets 72. Longitudinal expansion of the core assembly is thus freely permitted without stressing the supporting rods 73.

Respective swingable supporting rods 73 may be employed at the end tubular rivets 71, 71, and if necessary, additional supporting rods 73 may be employed at one or more of the intermediate tubular rivets.

While certain specific embodiments of electrical baseboard heating units have been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

1. In an electric air heater, a horizontally elongated housing having a lower horizontal air inlet and an upper horizontal air outlet and having substantially vertical front and rear walls, a heating unit comprising an intermediate horizontally elongated vertical plate member, respective additional horizontally elongated vertical plate members disposed on opposite sides of said intermediate plate member, an elongated electrical heating element substantially coextensive in length with and secured longitudinally on said intermediate .plate member, a pinrality of transverse tubular rivets extending through said plate members, and spacer sleeves on said rivets between the plate members and spacing said plate members in parallel relation, horizontal projections on the rear wall of the housing extending supportingly through said tubular rivets, and further projections on said rear Wall engaging the rearmost vertical plate member to space the heating unit from said rear wall.

2. 'In an electric air heater, a horizontally elongated housing having a lower horizontal air inlet and an upper horizontal air outlet and having substantially vertical front and rear walls, a heating unit comprising an intermediate horizontally elongated vertical plate member, respective additional horizontally elongated vertical plate members disposed on opposite sides of said intermediate plate member, an elongated electrical heating element substantially coextensive in length with and secured longitudinally on said intermediate plate member, a plurality of transverse tubular rivet-s extending through said plate members, and spacer sleeves on said rivets between the plate members and spacing said plate members in parallel relation, horizontal projections on the rear wall of the housing extending supportingly through said tubular rivets, a hook-like projection on said rear Wall extending through the upper portion of the rearmost vertical plate member and an additional projection on said rear wall engaging the lower portion of said rearmost plate member.

3. Inan electric air heater, a horizontally elongated housing having a lower horizontal air inlet and an upper horizontal air outlet and having substantially vertical front and rear walls, a heating unit comprising an intermediate horizontally elongated vertical plate member, respective additional horizontally elongated vertical plate members disposed on opposite sides of said intermediate plate member, an elongated electrical heating element substantially coextensive in length with and secured longitudinally on said intermediate plate member, a plurality of transverse tubular rivets extending through said plate members, and spacer sleeves on said rivets between the plate members and spacing said plate members in par allel relation, horizontal projections on the rear wall of the housing extending supportingly through said tubular rivets, a hook-like projection on said rear wall extending through the upper portion of the rearmost vertical plate member, an additional projection on said rear wall engaging the lower portion of said rearmost plate member to space the heating unit from said rear wall, and a horizontally elongated upwardly and forwardly inclined baffle plate secured in the top portion of the housing above said heating unit and facing said air outlet.

4. An air heating unit comprising a plurality of elongated parallel plate members including an intermediate plate member and additional plate memlbers disposed on opposite sides thereof, at least three longitudinally spaced transverse tubular rivets extending through said plate members, spacer sleeves on the tubular rivets between the plate rnembers,-said spacer sleeves being of progressively increasing diameters from the vertical center line of the unit toward the opposite ends thereof, and an elongated electrical heating element secured longitudinally on the intermediate plate member and being substantially coextensive in length therewith.

5. An air heating unit comprising a plurality of elongated parallel plate members including an intermediate plate member and additional plate members disposed on opposite sides thereof, at least three longitudinally spaced transverse tubular rivets extending through said plate members, spacer sleeves on the tubular rivets between the plate members, said spacer sleeves being of progressively increasing diameters from the vertical center line of the unit toward the opposite ends thereof, and an elongated electrical heating element secured longitudinally on the intermediate plate member and being substantially coextensive in length therewith, said electrical heating element comprising at least two spaced arms extending longitudinally on said intermediate plate member, said tubular rivets extending between said two spaced arms.

6. An air heating unit comprising a plurality of elongated parallel plate members including an intermediate plate member and additionalplate members disposed on opposite sides thereof, at least three longitudinally spaced transverse tubular fastening memlbers extending through said plate members, spacer sleeves mounted on the tubular fastening members between said plate members, and being secured to the intermediate plate members, said spacer sleeves being of progressively increasing diameters from the vertical center line of the unit toward the opposite ends thereof, and an electrical heating element secured on the intermediate plate member.

7. In an electric air heater, a horizontally elongated housing having a lower horizontal air inlet and an upper horizontal air outlet and having substantially vertical front and rear walls, a heating unit comprising an intermediate horizontally elongated vertical plate memlber respective additional horizontally elongated vertical plate members disposed on opposite sides of said intermediate plate member, an elongated electrical heating element substantially coextensive in length with and secured longitudinally on said intermediate plate member, a plurality of transverse tubular rivets extending through said plate members, and spacer sleeves on said rivets between the plate members and spacing said plate members in parallel relation, horizontal projections connected to the housing and extending supportingly through said tubular rivets, and additional means connected to the housing and engaging the rearmost portion of the heating unit to space the heating unit from said rear wall.

(References on following page) References Cited in the file of this patent FOREIGN PATENTS 440,301 Great Britain Dec. 24, 1935 UNITED STATES PATENTS 458,569 Great Britain Dec. 22, 1936 1,721,099 W g n uly 16, 929 937,358 France ar. 3, 194

2,019,913 Kot-rbaty Nov. 5, 1935 5 

